124 



LICHENACKI. 



[PYCNOTHEUA. 



As limited, this is a very natural tribe, readily known by the form of 

 the thallus and the character of the variously coloured, but never normally 

 black, apothecia. The five genera of which it is composed, as constituted 

 by N"ylander (two of which, viz. Heterodea and Cladin, are exotic), while 

 closely related to each other, are separated by the basal thallus and the 

 podetia. The species are for the most part very social in habit. 



31. PYCNOTHELIA 



Duf. Bory Ann. Sc. Phys. 

 (1821) viii. p. 45; Ach. 

 Lich. (1810) p. 571 (ut 

 sectio Cenomyces). 

 Thallus crustaceous at 

 the base, persistent ; 

 podetia papillaeform, 

 simple or branched, cor- 

 ticate, glabrous. Apo- 

 thecia small, terminal on 

 the podetia ; spores 8nae, 

 oblong, simple, colour- 

 less ; thecse, especially 

 the apices, bluish with 

 iodine. Spermogones 

 normally terminal on the 

 podetia, conical ; sper- 

 matia cylindrical, and 

 somewhat acute at either 

 apex, or slightly arcuate. 



Fig. 34. 



Pycnothelia papillaria Duf. a. Sections of 

 apotheeia, X30. b. A theca and paraphysis, 

 X350. c. Spores, X500. d. Section of a 

 spermogone, x30. e. Sterigmata and sper- 

 matia, X500. 



Though usually regarded as a section, or at most a subgenus of Cla- 

 donia, this seems a distinct genus characterized by the crustaceous thallus 

 and papillate podetia. The texture of the thallus is entirely that of 

 Cladonia (vide Nyl. Syn. i. pp. 188, 189). 



1. P. papillaria Duf. Bory Arm. Sc. Phys. (1821) viii. p. 46. 

 Thallus granulose at the base, forming a more or less effuse crust, 

 whitish or pale yellow -greyish ; podetia short, clavato-cylindrical or 

 cylindrical, very fragile, egranulose, simple or subsimple, white or 

 glaucous (K + yellowish, CaCl ). Apothecia at first somewhat plane 

 and marginal, at length convex, solitary or aggregate, brown or 

 reddish-brown ; spores 0,009-0,014 mm. long, 0,0045 mm. thick. 

 Sm. Eng. Fl. v. p. 241 ; Gray, Nat. Arr. i. p. 424 ; Cromb. Lich. Brit. 

 p. 18 ; Leight. Lich. Fl. p. 55, ed. 3, p. 52. Cladonia papillaria 

 Mudd, Man. p. 52; Brit. Clad. p. 34. Cenomyce papillaria Tayl. in 

 Mack, Fl. Hib. ii. p. 82. Lichen papillaria Ehrh. Phyt. (1780) 

 n. 100 ; Dicks. Crypt, fasc. i. p. 13 ; With. Arr. ed. 3, iv. p. 45 ; 

 Eng. Bot. t. 907. Coralloides minimum fragile, Madreporce instar 

 nascens Dill. Muse. 107, t. 16. f. 28. Brit. Exs. : Leight. n. 208 ; 

 Mudd, n. 22, Clad. n. 80: Cromb. n. 121. 



The thallus in more barren habitats is somewhat determinate, and 

 the podetia are often subverrucseform, usually somewhat scattered, though 



